A Novel Preparation Method for Effervescent Tablets of Xianganfang Containing Fresh Juice using a Semi-Solid Extrusion 3D Printer with Three Cartridge Holders.

This study aimed to prepare effervescent tablets of traditional Chinese medicine Xianganfang with fresh juice using a semi-solid 3D printer with three cartridge holders to seperate acid and alkali source by drug paste through model design to avoid sticking impact and premature effervescence during the tableting in the conventional preparation process. The powder of Xianganfang including fresh juice of Phyllanthus emblica and licorice extract was obtained by vacuum freeze-drying with 50% mannitol as cryoprotectant. Then, the formulation of 3D-printed effervescent tablets was investigated. Further 5% HPMC hydroalcoholic gel was mixed with sodium bicarbonate and freeze-dried Xianganfang powder to prepare alkali source and drug paste respectively while 30% PVP ethanol solution was mixed with tartaric acid to prepare acid source paste; these three pastes had good printability. The pastes of drug, acid, and alkali were loaded into three syringe cartridges separately and numbered as "3," "5," and "7," according to cartridge holders of the 3D printer, and printed in the order of "537,353,735" for separating acid and alkali by drug to avoid premature effervescence. And the basic printing parameters were optimized. The tablets were evaluated by the appearance, tablet weight variation, hardness, disintegration time, friability, pH, and stability. The physicochemical properties all conformed to the Chinese Pharmacopoeia 2020 edition. The content of the active ingredient gallic acid was 0.769 ± 0.019 mg/g. This study provided a new method to prepare effervescent tablets of traditional Chinese medicine with fresh juice using 3D printing technology.

[Electrophysiological study on skeletal muscle by repetitive pulse stimulus].

This experimental study was designed to unravel the relationship between muscle tension and its electrophysiological property. The experiments on repetitive pulse stimulus in different current intensity to rabbit's motor nerve were performed in different pulse frequency by electromyography which applied electrical pulses and excited the tibial nerve, and by Instron 5544 machine which measured muscle tensions. The experimental data revealed that the tension force varied with the stimulus frequency in a quasi-parabolic relation, while it seemingly increased little with the stimulus intensity.